Acute Osteomyelitis / Septic Arthritis Flashcards
Incidence of AHO and Septic Arthritis
AHO=1/5000 Septic arthritis 1/2500 Poor outcome in 27% Most common m/o= Staph A 20% need surgery
Acute OM is more common in children compared with adults Why
AHO occurs in the metaphysis of long bones Knee common
Vascular differences sluggish blood flow
Cellular anatomy less phagocytosis in low pO2
Trauma 30%
Outcomes of AHO
1 bone destruction. Regeneration can occur unless blood supply +/or bone periosteum destroyed
2 Cartilage destroyed. Can only repair by scarring
Loss of function structure growth effected
Joint dysfunction
Clinical presentation of AHO
Fever 60% unwell child
POINT BONY tenderness cardinal sign
Redness wrath swelling
Investigations in AOH
FBC/Diff 35% of kids have raised WCC ESR goes up in 48hours peaks 3-5days ESR>55 ?subperiosteial abscess CRP up with in 24hours pearls 2 days Blood cultures +ve 50% of cases Plain X-RAY not much change till day 10 peiosteal reaction ? USS may show fluid collection ? Sub periO abscess or adjacent Septic A Bone SCan 84% diagnostic Useful if ? Multifocal/ equivocal tests, signs/ neonate /difficult locations eg spine/pelvis MRI useful Equivocal bone scan Soft tissue or marrow edema Abscess formation Pelvic infection Joint fluid
Treatment of AHO
Antibiotics IV for 3 days and then oral for 3-4/52 Rest If does not settle Surgery indications aspiration of the MCS (MRSA) Drain the abscess Drain the joint sepsis Debridement of dead tissue Biopsy. DD Leukemia / lymphomas
Subacute OM
More common
Delayed diagnosis
Slow onset intermittent pain generally well
Normal CRP/ESR
Usually in the metaphysis but can be the Epiphysis
DD. Leukemia/lymphoma
Chronic OM
Long term changes in the bone
Pathological fractures
Ischemia means hard to get the antibiotics to penetrate
Dead bone harbors microorganisms
Treatment is clean the dead bone and increase the blood supply
And antibiotics
Septic arthritis 3 routes are
1 blood born to the synovium
2 direct from AHO into the joint
3 trauma /direct innoculation
Which joints in Septic Arthritis
Knee and hip 70%
Ankle 13%
Shoulder 8%
Signs of Septic arthritis
Acute onset irritable HIGH FEVERS
Refuse to weight bear or limping ++ Severe pain
Joint hot and swollen
Investigations
FBC WCC>12000 ESR >50 ,CRP raised Blood cultures 30-50% X-rays not much help USS useful effusion Y/N ? Cause of effusion Synovical fluid MCS
Treatment of Septic Arthritis
1 Clean the joint
Aspiration
Arthroscopy
Or arthrotomy
2 Anitbotics
Septic arthritis in neonates
Immature immune system minimal or absent signs
Normal WCC/ CRP/ESR
Septicemia can cause multifocal infections ( need a bone scan)
Growth plate weaker so quicker to the joint
Staph A / GBS/E coli
DD of AHO or Spetic arthritis
Trauma Tumor. Eosinophils granuloma Ewings osteosarcoma Leukemia Chondroblastoma
